It is well known that aqueous solutions of sodium aluminate have a strongly alkaline reaction. Aqueous solutions of sodium aluminate, therefore, will react with carbon dioxide according to the equation: EQU 2NaAlO.sub.2 + 3H.sub. 2 O + CO.sub.2 .fwdarw. Na.sub.2 CO.sub.3 + 2Al(OH).sub.3
unfortunately when the reaction is carried out in this manner, the aluminum hydroxide is precipitated in a bulky, gelatinous form which occludes large volumes of liquor, containing product sodium carbonate, and is very slow to filter. Variations in temperature, concentration, stirring or rate of addition are not effective in yielding a precipitate which can be handled practically on an industrial scale. A further disadvantage of the process is that it yields sodium carbonate as an aqueous solution which must either be concentrated and dried, or employed as an aqueous solution, which in many applications would result in an undesirable dilution.